fsetid checks are triggered by chmod on a directory or file owned by
a group other than one of the groups assigned to the current process
to see if the setgid bit should be cleared, regardless of whether the
setgid bit was even set.  We do not appear to truly need this
capability for netd to operate, so remove it.  Potential dontaudit
candidate.

Change-Id: I5ab4fbaaa056dcd1c7e60ec28632e7bc06f826bf
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>